...Have you been introduced to my friend Hubris? Oh yes, she is quite lovely, isn't she? Single, too.
What is a nuclear weapon, anyway?
That was the letter signed by Albert Einstein & written by Leó Szilárd that ultimately led to the Manhatten Project, which prototyped and detonated the weapon (named 'Trinity') which produced the explosion seen at the top of this post. That was a small, very inefficient bomb, with a 'mere' 20 kiloton yield. For a direct comparison to conventional TNT, this overhead photograph shows the post-detonation Crossroads test site, where 108 tons of TNT were exploded as a benchmark for the Trinity test:
The TNT created the '0,1 KT test crater'.
Nuclear weapons use a runaway fission reaction to create explosions that are, ton for ton, orders of magnitude larger than can be created by any other man-made explosive. Crude fission bombs are frighteningly simple to create, now that the general principles are understood:
Surround a critical mass of plutonium with shaped explosive charges, and set the charges off simultaneously. You'll produce a kilton-yield reaction with surprisingly little material.
Multi-megaton hydrogen bombs are not as easy to produce, but are 'overkill' in many respects and in some ways are less dangerous than kiloton yield bombs because they shoot their 'fallout' (the radioactive debris from all of the burned people, buildings, cars, etc) very high into the atmosphere, where it's dispersed into extremely diluted concentrations before raining back to the Earth.
A much more detailed description of how fission bombs work has been provided by CptHamilton:
Are terrorists with briefcases containing nuclear bombs a real possible threat?
Normal, lower-yield nuclear weapons use a conventional explosive to create a run-away fission reaction in a fissile core. The reaction rapidly depletes the fissile fuel and extinguishes itself. The reaction has to be extremely fast to achieve the kind of expansion needed for a weapon, which places an upper limit on how large a quantity of fissile material you can detonate. Past a certain point, C4 simply isn't going to energize enough of the material to induce a fast enough fission cascade that all of the material undergoes fission and expels energy in the blast. Instead you'd have an explosion and then something like an un-shielded nuclear reactor core sitting there on the ground being hot as shit.
You can improve the effectiveness of the weapon using a 'boosted' fission process, wherein some easily-fused material (tritium, for example) is placed in the fissile core of the bomb. The energy of the fission reaction is sufficient to compress the fusion fuel and initiate a fusion reaction. The fusion reaction produces a bunch of high-energy neutrons, which then kick off fission in the un-reacted fissile material. Only 1.4 and 17%, respectively, of the fuel in the (un-boosted) bombs dropped on Japan was consumed.
A hydrogen bomb is essentially a boosted fission bomb with a big chunk of fusion fuel stuck on it. Conventional explosives kick off a boosted fission reaction. Energy from the fission reaction is transferred to a reserve of fusion fuel (tritium or deuterium; both isotopes of Hydrogen that are much easier to fuse than standard Hydrogen) inside of a fission-resistant sheath. The compressed fuel undergoes nuclear fusion and the resulting energy blows stuff up. But it won't fuse any ambient Hydrogen in the process; once the tritium fuel is expended, the reaction stops.
Not really. On paper, it's theoretically possible to contain a critical mass of plutonium and enough C4 to cause a chain reaction in a large duffel bag (you couldn't make a U-235 bomb and stick in a duffel bag. It would just be way too big). In reality:
1) Plutonium is extremely toxic, unstable & dangerous to handle outside of rigorously controlled environment (and even in those environments, there have been lethal accidents involving plutonium cores). Anyone building a duffel bag bomb in their basement would very likely die of radiation poisoning before completing the project, and / or accidentally allow the plutonium to decay to a non-explosive state.
2) Such a device would be too heavy to carry. Between the explosives, the critical mass and the casing needed to ensure a symmetrical explosion, nobody is going to be casually lugging something like that to a park or putting it on an aircraft or bus.
3) Plutonium is not easy to come by. It's a man-made element that decays rapidly, so you can't just steal some from a mine or civilian reactor. You need expertise & high tech facilities to produce it.
4) A duffel-bag sized device would require substantial engineering knowledge for miniaturization of it's non-critical components.
It's not out of the question that a terrorist state
might be able to crudely deliver a low-tech fission bomb to a neighboring country and set it off, say via a transport truck or boat, but the 24
notion that an individual could smuggle a small nuclear weapon into your city under the cover of nightfall is an ignorant fantasy.
I hear MAD all of the time. Why you so MAD, bro?
MAD is an acronym for 'Mutually Assured Destruction' - the supposed keystone of the Cold War. The United States and Soviet Union each had a variety of bomber and missile forces ready to strike at a moment's notice (or so goes the popular claim; there's plenty of reason to doubt it, now that we've had the chance to view to Soviet archives), and this was paradoxically (again, so goes the story) both the gravest threat to the world and the thing that prevented a single missile from taking flight: each side knew that if they tried to strike their opponent, they would be anihilated in turn. Thus, 'Mutually Assured Destruction'.
MAD is another one of those things much different in practice than on paper. There was at least one occassion where a nuclear attack submarine was given launch codes an an order to attack from the Kremlin; the commander of the boat simpy refused to follow the order. There were probably similar incidents on the American side of things, but we don't know because the records are sealed and will probably remain sealed indefinitely.
Who has nukes? Who is supposed to have nukes? Why does anyone have nukes?
The U.S., UK, France, China, Russia, India, Pakistan and North Korea have confirmed nuclear weaponry. Israel is highly suspected to have them, but insists it does not.
South Africa had a nuclear weapons program, but ultimately did the grown-up thing and abandoned it / dismantled the warheads.
All of the old Cold War players began reducing their nuclear arsenals once tensions began to relax, and the reductions have increased over the years. America's current stance is that it will always maintain a reserve of warheads for 'deterrent' (a nice of way of saying that they will use them if some vaguely defined conditions for mass murder of civilians are met), while the UK, France and China essentially follow the same trend without outright stating it. Pakistan & India are involved in their own miniature sort of Cold War regarding their arsenals (though even they have pedged to draw down their warheads and not expand their arsenals), while North Korea and Israel are in a somewhat enigmatic state where they plainly have fission bombs but have not made their intentions clear are not really trustworthy even if they did.
The international non-proliferation treaty seeks the abolishment of all
nuclear weapons, period, and the creation of a mandate for making the production of such weaponry illegal (the equivalent of a war crime). The United States feels that it ought to have more or less exclusive control over the trafficking of fission bombs. The UK & France have a very libertarian outlook (that everyone should be able to produce them... well, almost everyone. Everyone except the brown people, because who can trust them?
). Most other countries take the stance that, regardless of what anyone else does, they have a right to build and use nuclear bombs if they want, and the non-proliferation treaty can go fuck itself.
So, basically, it's a self-centered clusterfuck. Each country feels like they should have them and nobody else should, because everyone feels like they are the smartest guy in the room and thus the most capable of handling a technology that, in reality, human beings are not really responsibe enough to handle at all.
What is a \nuclear winter'? Could we really destroy the planet with our bombs?
Well, we couldn't literally blow apart the Earth with our nuclear arsenals; we could just render it uninhabitable, or destroy so much of our infrastructure that modern civilization collapses (might eventually recover, might not). Nuclear winter is a theoretical side-effect of a full exchange of multi-megaton ICBMs between countries - if the explosions shot enough material from cities & refineries into the upper atmosphere, it could cause a positive feedback loop that sends the Earth into a severe ice age (the sort that once upon a time produced 'snowball Earth'. The science is a bit dodgy and it's a disputed topic (mostly the arguments surround whether or not nuclear blasts would send sufficient volumes of ash high enough into the atmosphere), but it was popular among academics during the cold war because of the size of the bombs in circulation and the real threat of an extreme attack / counter-attack.
Nowadays, nuclear winter is - essentually - an impossibility.
So, let's talk bombs. Big bombs.